The present invention relates to a plasma processing apparatus for applying an etching processing to a processing-target substrate-like sample by using plasma formed within a processing chamber. Here, an example of this kind of sample is a semiconductor wafer located within the processing chamber inside a vacuum vessel. More particularly, it relates to a plasma processing apparatus which is equipped with a configuration for adjusting a processing condition for another different wafer by using a detection result of the etching processing.
In a plasma processing apparatus used in the semiconductor-device fabrication process, and in particular, in a plasma processing apparatus for applying an etching processing to the film structure located on the surface of a sample such as a semiconductor wafer, the wafer's etching machining is generally performed in accordance with the following process: Namely, an etching gas is introduced into a vacuum container. Next, plasma discharge is generated under a reduced-pressure condition. Moreover, radicals or ions, which are generated within this plasma, are caused to react with the wafer surface, i.e., the target to be processed. In the technologies like this, however, there has been a significant increase in the influence of a variation in the machining result by the etching processing with respect to a variation in the processing condition. Here, this significant increase has arisen in recent years in accompaniment with the microminiaturization of semiconductor devices. Accordingly, even if the plasma processing apparatus performs the etching processing of plural pieces of wafers using a constant set recipe, various types of outer disturbances occurring during the etching processing have prevented the resultant configuration by the machining (which is obtained as a result of the etching processing) from being formed and obtained with a high reproducibility maintained. As a consequence, it has become increasingly difficult to obtain the stable etching-machining performance.
The technology which has been considered as a one for solving the problems like this is as follows: The judgment on the end point of the etching processing is made by detecting a phenomenon which is specific to the development of the etching processing from the light-emission within the plasma generated inside the processing chamber. As the technology concerning the judgment on the end point like this, there has been known a technology disclosed in, e.g., JP-A-2009-206275. According to this related art, the high-accuracy end-point judgment can be implemented in accordance with the following process: Namely, a regression straight line regarding data about intensity of the light-emission of the plasma is created, using the data which is detected from the light-emission acquired during time-period of the etching processing. Next, the above-described judgment can be implemented by taking advantage of the distance between this regression straight line and time-sequence data about the intensity of the light-emission which is sequentially detected during the detection.